You must be managing without the advanced features, or not using a spreadsheet. Try becoming proficient with Pivot Tables in Excel and then trying to do pretty much anything more than simply creating a Pivot Table in OpenOffice. Most of Excel's Pivot Table features are missing from OpenOffice. Likewise, Autofiltering is very crippled when you're using OO and you've become dependent on Excel's capability.
I can respect the monetary savings that can be had in using OO when one doesn't actually need the advanced features, but it isn't accurate at all to claim that OO is as capable or advanced as MS Office. Don't get me wrong, I don't think MS Office is a bargain at all. It is fucking expensive. This is a cost of doing business when you need those features. And if you do need those features, you can't get by with the free alternative. In that case, it isn't foolish at all to pay the extra money.